Neural prosthetic devices are artificial extensions to the body that restore or supplement nervous system function that was lost during disease or injury. Particular success has been realized in the cochlear prostheses development. In contemporary cochlear implants, however, the injected electric current is spread widely along the scala tympani and across turns limiting the number of effective hearing channels. In this Phase 1, we propose an innovative optical cochlear stimulator (OCS) that can increase the number of channels which will ultimately improve the fidelity and research tools of cochlear implants. The first aim is Aculight will develop an optical cochlear stimulator based on previous models and experiments Northwestern University has completed. The methods for the first aim will use Aculight's previous experience with optical nerve stimulators in order to update the electrical and optical designs for use in cochlear implant research. The second aim, Northwestern will test and determine optimal parameters for development of an implantable optical cochlear stimulator. The methods for the second aim will use gerbils to determine the effectiveness and optimize the parameters of the OCS. The outcome of this grant will be a prototype OCS and optimal cochlear implant design parameters that can be implanted in an animal model in the Phase 2 project. This project is intended to benefit those that have lost hearing through disease or injury by developing a tool for research in cochlear implants as well as developing an improved cochlear implant. This research will focus on enhancing the performance of the cochlear implant to allow people to hear speech in a crowded room and even to hear music. [unreadable] [unreadable] [unreadable]